Often times following balloon angioplasty, it is necessary to insert a coronary stent into the artery to keep the artery open. On occasion it is necessary to remove the stent from the artery. There are a number of devices that have been proposed for this purpose. One is shown in U.S. Pat. No. 5,098,440 Hillstead which is a loop device for engaging the stent and removing it. Another is U.S. Pat. No. 5,464,408 Duc which utilizes two flexible tubes with a number of gripping members which are part of the inner tube which are directed to engage the stent and pull it into the outer tube. U.S. Pat. No. 4,990,151 Wallsten shows a stent removal device where the portion which engages the stent is straight and would not expand the artery to permit the stent to be drawn back more easily.
In balloon angioplasty, a small radiopaque guidewire is steered through a coronary guiding catheter and down a coronary artery past the area of blockage and over the wire. The physician then passes a thin flexible tube with a balloon at the end of it into the blocked artery. By inflating the balloon, the plaque causing the blockage is pressed back against the artery wall. Doing this, of course, opens the artery and increases the blood flow through the artery to the heart muscle. When the coronary stent is introduced into the blood vessel, it is collapsed down upon the balloon catheter until it reaches the narrow area of the artery. Sometimes, however, the stent may slip back off the balloon or become dislodged in the placement process and must be retrieved.